The present invention relates to a plasma display panel, in particular to a face-discharge AC driving plasma display panel.
Recently, it has been expected that a face-discharge AC driving plasma display panel can be utilized as a color-display apparatus having a large surface area but a small thickness. FIG. 7 is a cross sectional view indicating a cross sectional structure of such a face-discharge AC driving plasma display panel.
Referring to FIG. 7, a plurality of row electrode pairs 2,2 are provided on an internal surface of a front glass base-plate, a dielectric layer 3 is formed to cover the row electrode pairs 2, 2, a protection layer 4 of MgO is formed to cover the dielectric layer 3. In detail, each electrode 2 of a row electrode pair includes i) a transparent electrode 2a made of ITO or SnO.sub.2 transparent film and having a relatively a large width, ii) an auxiliary metal electrode 2b (a bus electrode) made of a metal film having a relatively small width. Such a bus electrode 2b is provided to compensate for the electric conductivity of the transparent electrode 2a.
Referring again to FIG. 7, column electrodes 6 are provided on an internal surface of a rear glass base-plate 5, a fluorescent layer 7 is formed to cover the column electrodes 6.
In this way, the row electrodes 2 provided on the internal surface of the front glass base-plate 1 and the column electrodes 6 provided on the internal surface of the rear glass base-plate 5 are arranged to be orthogonal with each other. An electric discharge space 8 is formed between the front glass base-plate 1 and the rear glass base-plate 5. A rear gas is introduced and sealed into the discharge space 8. Thus, each intersection formed by a row electrode 2 and a column electrode 6 serves as a center for the formation of a picture element (unit luminous area).
The above dielectric layer 3 is formed by coating the row electrodes 2 with a low melting point glass paste containing PbO followed by calcination. Further, since an electric resistance should be low in order to compensate for an electric conductivity of the transparent electrode 2a, the metal film for forming the auxiliary metal electrode 2b is required to contain Al or Al alloy.
FIG. 8 is an enlarged explanatory view illustrating row electrode pairs when viewed on a display side of a plasma display panel.
Referring to FIG. 8, each row electrode 2 includes a transparent electrode 2a and a bus electrode 2b laminated over the transparent electrode 2a. In each unit luminous area 12, a pair of transparent electrodes 2a, 2a have a pair of protruding portions 10, 10 which are facing each other through an electric discharge gap 11.
However, there are at least the following problems with the conventional plasma display panel shown in FIGS. 7 and 8. Namely, If the above dielectric layer 3 is formed by a low melting point glass containing PbO, such a dielectric layer 3 will react with the auxiliary metal electrode 2b, undesirably generating gas bubbles on an interface therebetween. Such gas bubbles will in fact cause the thickness of the dielectric layer 3 to become partially thinner, resulting in an undesired discharge due to a deterioration of high voltage durability. Consequently, the electric insulating property of the dielectric layer 3 will be damaged. Moreover, since the dielectric layer 3, which contains lead oxide (PbO) as a main component, has a relatively large specific dielectric constant 9-12, the cell capacity thereof is relatively large, so that the discharging current is needed to be large, resulting in a high consumption in electric power.
In order to solve the above problem, it has been suggested that the dielectric layer 3 be formed of a low melting point glass which contains an alkali glass as a main component and has a lower dielectric constant. However, during the calcination of an alkali glass, when glass material having a high ion-conductivity gets in contact with the transparent electrically conductive film which constituting the transparent electrode 2a, it is possible that the transparent electrically conductive film, the alkali glass and the aluminium will form a local battery system, hence corroding and discolorating (blackening) the transparent electrically conductive film, deteriorating the luminous efficiency.